block/blk-throttle: Add WQ_PERCPU to alloc_workqueue users

This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:

   commit 128ea9f ("workqueue: Add system_percpu_wq and system_dfl_wq")
   commit 930c2ea ("workqueue: Add new WQ_PERCPU flag")

The refactoring is going to alter the default behavior of
alloc_workqueue() to be unbound by default.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU. For more details see the Link tag below.

In order to keep alloc_workqueue() behavior identical, explicitly request
WQ_PERCPU.

Cc: Josef Bacik <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/all/[email protected]/
Suggested-by: Tejun Heo <[email protected]>
Signed-off-by: Marco Crivellari <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: DispatchCode

block/blk-throttle.c

@@ -1839,7 +1839,7 @@ void blk_throtl_exit(struct gendisk *disk)
 
 static int __init throtl_init(void)
 {
-	kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0);
+	kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM | WQ_PERCPU, 0);
 	if (!kthrotld_workqueue)
 		panic("Failed to create kthrotld\n");